Help with mileage - Page 2

saline · 09-22-2008, 09:22 AM

Hey Lactic, saw your rig down from my house at Aspen St Coffee in Fruita the other day, as well as Mary's Loop. Nice truck! Hope you had a good ride!
Josh

jeff@work · 09-22-2008, 10:11 AM

Where are you driving? In my travels i've found that the different formulations of gas can easily make a 1-2 mpg difference. Basically in areas with the 10% ethanol blend i see the lower mileage.

Has your speedometer been recalibrated for the larger tires? Check it against gps to make sure, maybe you're actually going more miles than you think you are...

What gears are you running? I have the 5.4 v8 and only have 3.73 gears. I'm pretty sure i'd underpowered trying to run a 34" tire. Hopefully you're van at least has 4:10's...

I only run 265/75r16's but I usually see anywhere from 12-15 mpg and if i'm doing ~55 mph it's usually 14-15.

If you're running around with bikes or something else like that on the roof it would probably hurt your mileage as well.

lactic · 09-22-2008, 08:01 PM

Hey Saline! Stop by for a beer next time you see us around! We usually camp out at 18 Rd, hit Loma on Saturday for laps, and a morning of the 18 Rd trails before heading out around 1 PM on Sunday.

adventureduo · 09-22-2008, 08:31 PM

Lactic your my hero with that gas mileage. That's just awesome.

lactic · 09-22-2008, 08:37 PM

Jeff@work's comment about adjusting the speedo for tire size has me thinking though.

If the speedo is not adjusted for the tires (speedo says 60 mph, GPS says 65 mph- verified by state trooper in southern Utah unfortunately), am I correct to assume the data coming from the engine and going to the Scanguage is also incorrect?

Once again, ignorance is bliss...

sdwindansea · 09-22-2008, 08:44 PM

Quote:

Originally Posted by lactic

Jeff@work's comment about adjusting the speedo for tire size has me thinking though.

If the speedo is not adjusted for the tires (speedo says 60 mph, GPS says 65 mph- verified by state trooper in southern Utah unfortunately), am I correct to assume the data coming from the engine and going to the Scanguage is also incorrect?

Once again, ignorance is bliss...

Yes you are correct that the ScanGauge would be incorrect. However, the ScanGauge has a way to adjust (by percentage) the speed displayed so you can make it accurate.

lactic · 09-22-2008, 09:04 PM

After figuring the system variance at 60 mph as per the speedo/GPS, my best guess on the modified overall gas mileage would be around 13.8mpg. Not horrible but I'll take the 15 any day!

One of you scientists want to check my 3rd grade math skills?

(Three beers in as I write this...)

skrivan · 09-24-2008, 03:55 PM

i think you need to "calibrate" the scangage. I did it mine and it improves the reported gas mileage. I dont use the scan often enough to tell you how the calibration is supposed to be done without having it in front of me (go to 'settings', then 'engine' or something and you plug in a %). i do know this: i checked the ScanGage with cruise control set at exactly 60 MPH (per Scangage)----after i clicked off 10 miles measured by highway mile-markers, it was 10 minutes exactly. So, somewhere on here i was told that the calibration setting for the scangage was 87% or something like that for the 285-75 tires....anyway, i know this isnt very helpful, but better info is somewhere on this forum. Jack Burgess knows....

sdwindansea · 09-24-2008, 04:39 PM

Use this website to figure out the percentage change to your speedometer with new tire sizes - http://www.miata.net/garage/tirecalc.html.

For example, I changed from 245/75/16 to 285/75/16. This means my speedometer reading is now 7.8% too slow. In other words, if my speedometer reads 60 mph, then I'm really going 64.7 mph (according to the link above).